Various schemes and devices are employed in game machines, e.g., slot and pinball machines to provide presentation effects that appeal to a player's visual and auditory senses, or sense of touch to increase the player's interest in the game. A moving body such as a moving gadget may be provided in a game machine to provide a presentation effect that appeals to a player's visual senses in particular. For instance, a stepping motor may drive this kind of moving body. To achieve a certain presentation effect, a motor control device may displace the moving body by a predetermined amount at a predetermined speed in accordance therewith. The motor control device receives a control command that includes a target speed and target rotation, and the like from the host device, and controls the motor in accordance with the command.
However, the directed speed and the actual rotational speed of the motor may differ. Thus, one technique proposes transmitting the speed of a synchronous motor, and a digital signal pertaining to an input current or an input voltage outside the synchronous motor allowing the speed of the synchronous motor to be sentenced externally, whereby it is possible to control speed fluctuations in the synchronous motor (refer Japanese Patent Publication No. 2009-261041).